Inkjet recording system, since it realizes accurate recording with low cost, is in general widely spread. Recently, thanks to the improvement of hardware like inkjet head and of software like raster image processor, furthermore high-performance inkjet printers are developed. According to this development, a development of inkjet recording materials, which enable to record output images transferred from the printer with high quality image and which enable to be preservative over the long period of time, has been proceeding. Consequently, many display materials with use of inkjet recording materials for like billboard and display panel have been seen in the market.
Ink receiving layer of inkjet recording materials is mainly classified into two types: i.e. “void type” where porous inorganic particles for absorbing ink are bound with hydrophobic resin binder; and “swelling type” where hydrophilic resin itself absorbs ink. From the view point of drying property and water resistance of ink, the void type ink receiving layer is now becoming the mainstream.
However, as the void type inkjet recording materials having hydrophobic resin in the ink receiving layer thereof adopt an ink absorbing method by capillary phenomenon through holes of porous inorganic particles, the ink absorbent amount is limited. Thereby, for the application of commercial-use display materials which require to have high ink concentration and tone so as to be seen well from the distance, absorbent amount thereof is not sufficient. In order to increase the absorbent amount of the void type ink receiving layer, thickening the ink receiving layer can be considered. Nevertheless, since the void type ink receiving layer is made by the solution coating in the water-based solvent, from the view point of high boiling point of water and the bad coating property, the coating amount is limited, therefore it is not easy to realize to thicken the ink receiving layer.
On the other hand, as for ink receiving layers containing hydrophilic resin, the resin itself forming the ink receiving layers can absorb ink, this type of layer is excellent in ink absorption capacity and is suitable for the use of like display materials which require high ink concentration and tone.
Display materials are used under a harsh environment such as outdoor. When an inkjet recording material is used as a display material, in order to give damage resistance and weatherability, a surface protective layer needs to be provided. As an inkjet recording material which is capable to easily provide this protective layer, Japanese Patent Application Laid-Open (JP-A) No. 2002-67481 (JP '481) discloses an inkjet recording material. The base layer of the inkjet recording material is used as the surface protective layer thereof; this is obtained by back-printing (mirror-like printing) the images to the thermosensitive adhesive ink receiving layer, then thermally adhering the ink receiving layer to the subjects to be adhered.